CPV code 42515000 designates District heating boiler in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
42515000 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 42510000 (Heat-exchange units, air-conditioning and refrigerating equipment, and filtering machinery).